This invention relates to a cleaning broom of improved structure.
Brooms in which the working head is formed from vegetable or synthetic fibres notably comprise, in addition to the fibres, a core or support for the fibres and a handle connected to this support.
The support can be suitable for supporting fibres formed either from single bristles or from double bristles, i.e. bristles bent double. In addition, the support can be of varying structure, and can require very different methods for fixing the fibres and handle. The large variety of these methods, which themselves govern the quality of contruction and the cost of a broom of the said type, is understandable when it is considered that brooms are very widely used in all countries.
A list is given hereinafter of the main methods known to the applicants for contructing brooms.
1. Providing a support (of wood or plastics) with a certain number of fairly close bores, into each of which is inserted the end of a bunch of bristles, as in the case of the fixing for a brush.
2. Inserting the head of a layer of bristles into a support provided upperly with a bore for the handle. Adhesive resin is injected through the bore in order to join the bristles and support together into a single body.
3. Inserting a layer of bristles between the electrodes of a welder (resistance, ultrasonic etc.) to weld together the heads of the bristles. The welded region is inserted with sufficient tightness into a cap containing the bore for the handle.
4. Arranging a bristle layer of constant thickness around a support known as a core, which is covered by the bristles and is of an easily perforable type, or around an easily penetrated padding. The layer is supported by a ring fixed by nails which pass into the core and are bent over so as to lock and compress the assembly. A lower ring with bent metal claws is also usually provided to make the bristle layer even more compact.
5. Inserting a layer of bristles, bent double on a core, into a plastics cap and fixing it to the cap by two metal claws which pass through and are bent over on the other side so as to compress the assembly.
6. Butt-positioning of a layer of bristles around a core which preferably comprises three bores, and fixing the layer by a metal ring also possessing three opposing bores which correspond to those in the core, and using three rivets to compress the assembly. The central rivet is sometimes usefully replaced by a bolt which can also fix the cap with the bore for the handle.
The listed methods have considerable limits and deficiencies. The basic defect is the fact that craftsman-type methods are used in construction, because of which production is low and cost is high due to the considerable labour content. In this sense, the application of nails, claws, rivets, screws, stitching etc. by hand (or by elementary equipment or non-automatic machines) is very uneconomical.
In particular, stitching between the bristles is a cause of serious drawbacks because it requires the use of semi-automatic machines of low production, and because increasing stitching difficulties arise as the broom length increases. Finally, the bristles inevitably become slack after a short time, leading to a rapid deterioration of the broom.
The injection of adhesive resin (method 2) and the welding between resin bristles and the cap (method 3) are also carried out on a craftsmanship scale. Brooms constructed up to the present time have one common defect, namely the fact that their assembly, which is initially sufficiently stable, becomes very slack in a short time because during use it is necessary to frequently subject the broom to large impacts in order to remove foreign bodies embedded in or adhering to the bristles.